feat: initial MVP - FastAPI backend + Vue3 frontend + docker-compose

- backend: FastAPI + SQLAlchemy 2.0(async) + asyncpg + Alembic
- 7 API routes: auth/me/articles/sources/bookmarks/subscriptions/admin
- models: User/Source/Article/Bookmark/Subscription/ApiToken
- services: RSS fetcher (feedparser) + Tencent TMT translator with quota + cache + local NLLB fallback
- workers: APScheduler + asyncio pipeline (fetch -> dedupe -> insert -> translate)
- seed scripts: create_user, seed_sources (5 RSS: Reuters/BBC/Al Jazeera/NHK/DW)
- frontend: Vue 3 + Vite + Naive UI + Pinia + vue-router
- pages: Login, Feed (24h), ArticleDetail, Sources, Bookmarks, AdminSources
- deploy: docker-compose (postgres/redis/api/worker/frontend/caddy)
- docs: README, DEPLOY, architecture, acceptance

Caddyfile

@@ -0,0 +1,32 @@
+{
+    # 全局选项
+    auto_https off
+    admin off
+    log {
+        level info
+        output stdout
+    }
+}
+
+# 如果 DOMAIN 为空,直接走 80 端口 HTTP(自签证书后面再补)
+# 如果有域名,改用下面的 https 配置块
+
+http://{$DOMAIN:NEWS_DOMAIN_FALLBACK} {
+    reverse_proxy /api/* api:8000
+    reverse_proxy /* frontend:80
+
+    encode gzip zstd
+
+    # 日志
+    log {
+        output stdout
+        format console
+    }
+}
+
+# 如果有域名,启用自动 HTTPS(取消下面注释,并把上面块注释)
+# {$DOMAIN} {
+#     reverse_proxy /api/* api:8000
+#     reverse_proxy /* frontend:80
+#     encode gzip zstd
+# }